Throughout the descriptions herein, reference is made both to a proximal end and a distal end of various parts of a syringe. Proximal is the end closer to a user's (i.e., an operator's) body when operating a syringe. Distal is closer to the end from which fluid either exits the syringe during injection or enters the syringe during withdrawal.
A syringe typically contains several parts. One is a cylindrical barrel that is substantially hollow. Another is a plunger that partially fits within the hollow space of the barrel. Syringes are used to inject and/or withdraw fluids in various sectors such as, for example, laboratory, human medicine and veterinary medicine fields. The injection and/or withdrawal of fluids can be into/from a blood vessel, tissue, or other body region of a patient.
The plunger either pushes fluid out of the barrel during injection, or pulls fluid into the barrel during withdrawal. Many syringes have a hollow needle or cannula permanently or detachably connected at the distal end of the barrel. Injecting fluid from a syringe is accomplished by pushing the plunger further into the barrel, where the fluid is located. This action reduces the volume and forces fluid to be expelled through an opening of the barrel. Withdrawing fluid from an external source into a syringe is accomplished by partially drawing the plunger from the barrel to create a vacuum, which causes fluid to flow from the external source into the barrel. Typically, syringes have markings on the barrel that signify a quantity of fluid contained therein.
Some syringe plungers have a flange at the proximal end, herein referred to as a plunger flange. In conventional use, one holds or otherwise contacts a surface of the plunger flange to exert a proximal force and withdraw the plunger from the barrel during fluid withdrawal, or to exert a distal force and push the plunger further into the barrel during fluid injection. Some syringes have a flexible, elastomeric member, referred to herein as a sealing member, which fits over the distal-most end of the plunger and facilitates the creation of the vacuum as a user withdraws the plunger. For example, phlebotomy is the withdrawal of blood from a blood vessel, typically a vein. Fine needle aspiration (FNA) means the withdrawal of material from body tissue so that cells can be studied under a microscope. Arthrocentesis involves aspirating a joint to either collect a fluid sample for diagnostic purposes, or to drain effusions from the joint space. Phlebotomy, FNA, and arthrocentesis are situations in which an ergonomic syringe and adaptor would facilitate the withdrawal of fluids from a patient.
Various techniques and finger/hand positions are commonly used for moving the plunger in the proximal direction in order to create the vacuum that withdraws fluid from an external source into the barrel. In conventional operation, a user often must employ a two-handed technique, particularly for withdrawing fluid, in which the user grasps the outer surface of the barrel with fingers of a first hand, while grasping the plunger flange at the proximal end with fingers of a second hand. The user then holds the barrel in a relatively stationary position with the first hand while pulling or otherwise exerting force on the plunger flange in a proximal direction with the second hand to further withdraw the plunger from the barrel. However, a two-handed technique has several disadvantages. One is that, by grasping the plunger flange with one hand and the barrel with the other, the user does not have a free hand available to stabilize the patient's body region or part from which fluid is being withdrawn, which is important in many respects, including in veterinary medicine.
Therefore, instead of using both hands to operate the syringe, in some respects it is more desirable to use only one hand. A one-handed technique provides the user a free hand for performing additional tasks, such as holding onto and thereby stabilizing the patient's limb, tissue mass, or other body region. It is also desirable in some situations to have one hand free to handle other equipment that is used when fluid is withdrawn from a patient.
Notwithstanding, a conventional syringe, such as is generally commercially available and used by medical providers and laboratory personnel, does not facilitate a one-handed technique, especially for withdrawing of fluids. This is because, as a user withdraws the plunger flange proximally along the longitudinal axis of the barrel, the distance necessarily increases between the barrel and the plunger flange. In other words, since the plunger flange is located proximal to the barrel, in the direction that the plunger must travel, it requires the user to move his or her fingers through an over-extended range of motion in order to maintain a vacuum and withdraw the plunger thereby pulling fluid or cells into the barrel.
This maneuver can be difficult to accomplish for those with normal hand/finger dexterity, and may be impossible for those with limited hand/finger dexterity and/or strength such as one with arthritis, or whose fingers are relatively short in length. An ergonomic syringe and adaptor, as described herein, helps solve this difficulty. Also, because it is more effective to use the syringe in a one-handed technique, for example to withdraw fluids, the maneuver can be accomplished more ergonomically and rapidly. This reduces the amount of time that a patient must be restrained or encouraged to remain still. In an emergency, the time savings has the potential to improve outcomes. Likewise, an ergonomic syringe, and an adaptor for use with existing conventional syringes, reduce potential trauma to a patient's blood vessel, tissue, or other body region during withdrawal of fluids, given that there is greater efficiency in stabilizing the barrel and associated needle placement in a one-handed technique. Moreover, those with limited hand/finger dexterity, strength, or digit length may be able to accomplish the task of one-handed fluid withdrawal, whereas otherwise they may not be capable of doing so with a conventional syringe. Also, it is expected that repetitive use injuries to users may be reduced due to ergonomic improvements over conventional syringes.
It will be understood by those having ordinary skill in the art, that conventional syringes are designed primarily for injecting fluids, for example vaccines or medications. Such designs, however, are not as suitable for withdrawing fluids because of the direction of movement of the plunger. With a one-handed syringe technique, because the fingers must spread and become over-extended, it becomes more likely that a user's hand or fingers will slip from contact with the barrel and/or plunger flange during withdrawal. Additionally, as the distance increases, it becomes more difficult to apply sufficient force to the plunger flange, a task that some users (e.g., those having shorter fingers or limited dexterity and/or strength) may not be able to accomplish.